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Checking if the value of a textbox is changed or not

I have a textbox filled at the page load. I want to check the value of the textbox is changed or not in the "update" button press. Any solution? TIA.

Well, you could say use client side javascript.
But, you could also do this:
Say this text box:
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
<asp:Button ID="Button1" runat="server" Text="Done - continue" OnClick="Button1_Click" />
And our code could be this:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// code here to setup and load controls
TextBox1.Text = "Dog";
ViewState["TextBox1"] = "Dog";
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (TextBox1.Text != (string)ViewState["TextBox1"])
{
// then text box was changed
}
}

ASP.net textbox with range textmode keeps resetting it's value

Hi i am busy creating a asp.net project that needs to get three values from the user. I am using a textbox with a range textmode to get these values and the first time the user moves the slider it works perfectly but after that the user can.t adjust any of the textboxes anymore.
I tried using a slider extender but this does not seem to work and only a textbox shows.
my html code to create the textboxes and labels showing the value
body>
<form id="form1" runat="server">
<p>
Quantum 1 Length:
<asp:TextBox ID="txtVal1" runat="server" TextMode="Range" min="1" Max="8" OnTextChanged="txtVal1_TextChanged1" AutoPostBack="True"></asp:TextBox>
<asp:Label ID="lblVal1" runat="server" Text="/////"></asp:Label>
</p>
<p>
Quantum 2 Length:
<asp:TextBox ID="txtVal2" runat="server" TextMode="Range" min="1" Max="8" OnTextChanged="txtVal2_TextChanged1" AutoPostBack="True"></asp:TextBox>
<asp:Label ID="lblVal2" runat="server" Text="/////"></asp:Label>
</p>
<p>
Quantum 3 Length:
<asp:TextBox ID="txtVal3" runat="server" TextMode="Range" min="1" Max="8" AutoPostBack="True" OnTextChanged="txtVal3_TextChanged1"></asp:TextBox>
<asp:Label ID="lblVal3" runat="server" Text="/////"></asp:Label>
</p>
<p>
<asp:Button ID="btnNext" runat="server" AutoPostBack="true" Height="24px" OnClick="btnNext_Click" style="margin-left: 0px" Text="Next" Width="150px" />
<script type="text/javascript" __designer:mapid="129">
function NextPage() {
window.open('Execution.aspx', 'Execution');
}
</script>
<asp:Label ID="lblError" runat="server" ForeColor="Red" Text="Invalid input; Please ensure that Quantum 1 <= Quantum 2 <= Quantum 3" Visible="False"></asp:Label>
</p>
</form>
</body>
My C# code used to control the boxes and change their values
public partial class Quantums : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
try
{
txtVal1.Text = HttpContext.Current.Session["Q1"].ToString();
}
catch { }
try
{
txtVal2.Text = HttpContext.Current.Session["Q2"].ToString();
}
catch { }
try
{
txtVal3.Text = HttpContext.Current.Session["Q3"].ToString();
}
catch { }
lblVal1.Text = txtVal1.Text;
lblVal2.Text = txtVal2.Text;
lblVal3.Text = txtVal3.Text;
//UpdatePanel1.Triggers.Add(new AsyncPostBackTrigger() { ControlID = "btnNext" });
}
protected void txtVal1_TextChanged1(object sender, EventArgs e)
{
HttpContext.Current.Session["Q1"] = txtVal1.Text;
}
And then the same code for textbox 2 and 3. Any suggestions on why the textboxes vaklue keeps resetting and autopostback is enabled on all three buttons.

I just noticed you were missing if(Page.IsPostBack()) return;. Your problem is that every time you change your textbox, the 'Page_Load' event is enacted, then the respective event handler (see page life cycle). So you were setting the text to the sessions, then setting the sessions to the text, effectively doing nothing.
You actually don't need anything for this page in the Page_load method, at least for now. Try the following:
protected void Page_Load(object sender, EventArgs e)
{
}
protected void txtVal1_TextChanged(object sender, EventArgs e)
{
Session["Q1"] = txtVal1.Text;
lblVal1.Text = txtVal1.Text;
}
protected void txtVal2_TextChanged(object sender, EventArgs e)
{
Session["Q2"] = txtVal2.Text;
lblVal2.Text = txtVal2.Text;
}
protected void txtVal3_TextChanged(object sender, EventArgs e)
{
Session["Q3"] = txtVal3.Text;
lblVal3.Text = txtVal2.Text;
}
You can then access the user input values using the respective session values. For example:
protected void Submit(object sender, EventArgs e)
{
List<string> answers = new List<string>();
answers.Add(Session["Q1"].ToString());
answers.Add(Session["Q2"].ToString());
answers.Add(Session["Q3"].ToString());
// Do stuff with answers
}

how to use session to passing values between page c# ASP.NET web Forms

I'm a newbie in C# web api and I want to pass values between pages by using Session.
Here is my code.
page1.aspx
<asp:Label ID="lb_front" runat="server"></asp:Label>
<asp:TextBox ID="txt1" runat="server"></asp:TextBox>
<asp:Button ID="bt1" runat="server" OnClick="bt1_Click" />
page1.aspx.cs
protected void bt1_Click(object sender, EventArgs e)
{
lb_front.Text = txt1.Text;
Session["user"] = txt1.Text;
}
page2.aspx
<asp:Label ID="lb_top" runat="server"></asp:Label>
page2.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
lb_top.Text = "<img src='./Images_top/'"+ Session["user"]+"'.jpg'></img>";
lb_top.Text += Session["user"];
}
I want to use the session value in the path to display an image on the label, but this isn't working.

You have to set the image path dynamically like:
page2.aspx
<asp:Image runat="server" ID="image" />
<asp:Label ID="lb_top" runat="server"></asp:Label>
page2.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
string sessionValue = (string)Session["user"];
image.ImageUrl = "../Images_top/"+ sessionValue +".jpg"; // set image url/src from session
lb_top.Text += sessionValue;
}

ASP.NET - SelectedValue/Index in Listbox always changing after a postback

I've been wrestling with this problem for days and so far I haven't been able to find an answer that fits this specific issue. Here's the code to load the list in the PageLoad():
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
lstEmprendimientos.DataSource = Emprendimiento.DevolverEmprendimientosConEvaluacionesIncompletas();
lstEmprendimientos.DataValueField = "id";
lstEmprendimientos.DataTextField = "titulo";
lstEmprendimientos.DataBind();
pnlEvaluador.Visible = false;
}
}
The first method loads a list made up of 'Emprendimiento' objects, and on that list's SelectedIndexChanged I call another method to load a list through a method that uses the SelectedValue of the item selected.
My problem is that, no matter what I do, the SelectedIndex is always reset to 0 after a postback, so I can't load the second list using the SelectedValue properly. I've worked with lists for a long while now and I've never had this problem, so it's really baffling. I'd appreciate some help with this.
Here's the code for the whole page:
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
ddlEmprendimientos.DataSource = Emprendimiento.DevolverEmprendimientosConEvaluacionesIncompletas();
ddlEmprendimientos.DataValueField = "id";
ddlEmprendimientos.DataTextField = "titulo";
ddlEmprendimientos.DataBind();
pnlEvaluador.Visible = false;
}
}
protected void lstEmprendimientos_SelectedIndexChanged(object sender, EventArgs e)
{
}
protected void lstEvaluadores_SelectedIndexChanged(object sender, EventArgs e)
{
Evaluador ev = Evaluador.FindByID(lstEvaluadores.SelectedValue);
}
protected void btnAsignarEvaluador_Click(object sender, EventArgs e)
{
Emprendimiento emp = Emprendimiento.FindByID(Convert.ToInt32(ddlEmprendimientos.SelectedValue));
Evaluador ev = Evaluador.FindByID(lstEvaluadores.SelectedValue);
Evaluacion eva = new Evaluacion(emp, ev, 0, "justificacion", DateTime.Now, false);
if (eva != null)
{
if (eva.Insertar())
{
lblFeedback.Text = "Alta exitosa.";
emp.listaEvaluaciones.Add(eva);
lstEvaluadores.DataSource = emp.DevolverListaEvaluadoresQueNoEvaluanEmprendimiento();
lstEvaluadores.DataTextField = "Nombre";
lstEvaluadores.DataValueField = "Email";
lstEvaluadores.DataBind();
pnlEvaluador.Visible = true;
CargarEvaluadores();
}
else
{
lblFeedback.Text = "Error en el ingreso de datos.";
}
}
else
{
lblFeedback.Text = "Error en el ingreso de datos.";
}
}
protected void btnSeleccionarEmp_Click(object sender, EventArgs e)
{
CargarEvaluadores();
}
private void CargarEvaluadores()
{
Emprendimiento emp = Emprendimiento.FindByID(Convert.ToInt32(ddlEmprendimientos.SelectedIndex));
lstEvaluadores.DataSource = emp.DevolverListaEvaluadoresQueNoEvaluanEmprendimiento();
lstEvaluadores.DataTextField = "Nombre";
lstEvaluadores.DataValueField = "Email";
lstEvaluadores.DataBind();
pnlEvaluador.Visible = true;
}
protected void ddlEmprendimientos_SelectedIndexChanged(object sender, EventArgs e)
{
CargarEvaluadores();
}
Page markup:
<%Page Title="" Language="C#" MasterPageFile="~/masterPage.Master" AutoEventWireup="true" CodeBehind="asignarEvaluador.aspx.cs" Inherits="InterfazUsuario.asignarEvaluador">
<asp:DropDownList ID="ddlEmprendimientos" runat="server" OnSelectedIndexChanged="ddlEmprendimientos_SelectedIndexChanged">
</asp:DropDownList>
<br />
<br />
<asp:Button ID="btnSeleccionarEmp" runat="server" OnClick="btnSeleccionarEmp_Click" Text="Seleccionar emprendimiento" Width="195px" />
<br />
<br />
<asp:Panel ID="pnlEvaluador" runat="server">
<asp:ListBox ID="lstEvaluadores" runat="server" OnSelectedIndexChanged="lstEvaluadores_SelectedIndexChanged"></asp:ListBox>
<br />
<br />
<asp:Button ID="btnAsignarEvaluador" runat="server" OnClick="btnAsignarEvaluador_Click" Text="Asignar evaluador" Width="135px" />
<br />
<br />
<asp:Label ID="lblFeedback" runat="server"></asp:Label>
<br />
</asp:Panel>

You need to change your DropDownList and ListBox controls to AutoPostback
DropDownList
<asp:DropDownList ID="ddlEmprendimientos" runat="server"
OnSelectedIndexChanged="ddlEmprendimientos_SelectedIndexChanged"
AutoPostBack="True">
</asp:DropDownList>
ListBox
<asp:ListBox ID="lstEvaluadores" runat="server"
OnSelectedIndexChanged="lstEvaluadores_SelectedIndexChanged"
AutoPostBack="True">
</asp:ListBox>
AutoPostBack:
Set this property to true if the server needs to capture the selection
as soon as it is made. For example, other controls on the Web page can
be automatically filled depending on the user's selection from a list
control.
This property can be used to allow automatic population of other controls on > the Web page based on a user's selection from a list.
The value of this property is stored in view state.
https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.autopostback(v=vs.110).aspx

I found the problem after checking everything out again.
The DataValueField in the list was 'id', and the id field in the 'Emprendimiento' class wasn't defined, so it was always returning a null int (0). Thank you kindly for the help, it was just a dumb mistake in the end.

How to show/hide a button from server side?

I'm new to ASP.NET and C#, I tried few things but did not worked. I have an .aspx page where I have three buttons, as shown in below code:
<body>
<form id="htmlForm" runat="server">
<telerik:RadScriptManager ID="rsm" AsyncPostBackTimeout="1800" runat="server" />
<telerik:RadAjaxPanel ID="rap" runat="server" LoadingPanelID="ralp">
<table>
<tr>
<td colspan="2">
Invoice Download
</td>
</tr>
<tr>
<td>
Invoice Start #
</td>
<td>
<telerik:RadNumericTextBox ID="rntbStart" Runat="server" MaxValue="1000000" MinValue="1000" Width="75px" >
<NumberFormat DecimalDigits="0" GroupSeparator="" />
</telerik:RadNumericTextBox>
</td>
</tr>
<tr>
<td>
Invoice End #
</td>
<td>
<telerik:RadNumericTextBox ID="rntbEnd" Runat="server" MaxValue="1000000" MinValue="1000" Width="75px" >
<NumberFormat DecimalDigits="0" GroupSeparator="" />
</telerik:RadNumericTextBox>
</td>
</tr>
<tr>
<td colspan="2">
<asp:Button ID="cmdDownload" runat="server" Text="Download" />
<asp:Button ID="cmdDownloadSAP" runat="server" Text="Download SAP" />
</td>
</tr>
</table>
<asp:Label ID="lblResult" runat="server" Text=""></asp:Label>
</telerik:RadAjaxPanel>
<telerik:RadAjaxLoadingPanel ID="ralp" Runat="server" Skin="Default" />
<asp:Button ID="btnConform" Visible="false" runat="server" Text="Conform Download" OnClick="btnConform_Click" />
</form>
I'm trying to do that btnConform will be initially invisible while the page is loading and now if I click cmdDownload or cmdDownloadSAP, button btnConform must get visible. Now if I click again on btnConform it will become invisible.
I cannot use JavaScript because cmdDownload and cmdDownloadSAP have some other task to complete before I make btnConform visible (say database call) and the btnConform will become visible only if the database call is successful.
partial class XPO_Accounting_InvoiceDownload : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void cmdDownload_Click(object sender, System.EventArgs e)
{
Session["InvoiceStart"] = rntbStart.Value;
Session["InvoiceEnd"] = rntbEnd.Value;
try
{
//All DB call
btnConform.Visible = true;
}
catch (Exception ex)
{
lblResult.Text = ex.ToString();
}
}
protected void cmdDownload0_Click(object sender, System.EventArgs e)
{
Session["InvoiceStart"] = rntbStart.Value;
Session["InvoiceEnd"] = rntbEnd.Value;
try
{
//All DB call
btnConform.Visible = true;
}
catch (Exception ex)
{
lblResult.Text = ex.ToString();
}
}
override protected void OnInit(EventArgs e)
{
base.OnInit(e);
cmdDownload.Click += cmdDownload_Click;
cmdDownloadSAP.Click += cmdDownload0_Click;
}
protected void btnConform_Click(object sender, EventArgs e)
{
double InvoiceStart = (double)Session["InvoiceStart"];
double InvoiceEnd = (double)Session["InvoiceEnd"];
try
{
SqlHelper.ExecuteNonQuery(XPOStaticData.Instance.SQL, CommandType.Text, "update tblInvoiceNum set uploadedtoacct = 'Y' WHERE Status='I' AND InvoiceNum BETWEEN " + InvoiceStart + " AND " + InvoiceEnd + " and uploadedtoacct = 'N'");
lblResult.Text = "Downloaded Invoiced has conformed as the correct one.";
btnConform.Visible = false;
}
catch (Exception ex)
{
lblResult.Text = ex.ToString();
}
}
}
This does not work.
Sorry for change the content of the question (cause older content wasn't pointing the problem properly). This is actual code here I'm trying to do it. (it looks stupid to pest the complete code...)

Add the Visible property to the Button using markup to initially set the second button's visibility:
<asp:Button ID="btnOne" runat="server" Text="One" OnClick="btnOne_Click" />
<asp:Button ID="btnTwo" runat="server" Visible="False" Text="Two" OnClick="btnTwo_Click" />
And on the event handlers, add this:
protected void btnOne_Click(object sender, EventArgs e)
{
btnTwo.Visible = true;
}
protected void btnTwo_Click(object sender, EventArgs e)
{
btnTwo.Visible = false;
}

You change visibility with the Visible property:
protected void btnOne_Click(object sender, EventArgs e)
{
//require code to make it visible
btnTwo.Visible = true;
}
protected void btnTwo_Click(object sender, EventArgs e)
{
//require code to make it invisible
btnTwo.Visible = false;
}
If you want to make a server control initially invisible you also have to use this property, so you can either use codebehind to change visibility programmatically ore declaratively on the aspx-page:
<asp:Button ID="btnTwo" Visible="false" runat="server" Text="Two" OnClick="btnTwo_Click" />
One final note, Visible=false on serverside means that this control is not rendered at all on client-side. So it does simply not exist and can not be accessed (or made visible) on client-side.
If you need to access it on client-side you should make it invisible via stylesheets either by using
display: none(does not take up any space) or
visibility: hidden(still takes up space in the layout).
Update acc. to the last edit of your question the event handlers don't seem to be registered anymore.
So you need:
<asp:Button ID="cmdDownload" OnClick="cmdDownload_Click" runat="server" Text="Download" />
<asp:Button ID="cmdDownloadSAP" OnClick="cmdDownload0_Click" runat="server" Text="Download SAP" />